The drum machine does not have an input. My bass head is a Gallien-Krueger Backline 250, with only one inport jack. For some reason, when I tried bass to pedals to input, and drum machine to patch bay return, I got a really fuzzy sound (It actually sounded kind of cool though).

I think you're either going to need a Y-cable (two female to a single male connector -- I like those odds ) or an ABY switch. I had the same thing going into my GK 400RB-III through a Morley ABY and no problemo.